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The mmmg of alluvial gold involves many deposits of theMesozoic, Tertiary, and Quaternary Ages in processing. Majorfeatures of the composition of such alluvial deposits are the lowcontent of gold and the small size of the gold particles. Atpresent, the gold-miners treat alluvial deposits in which a portionof fme gold (0.25 mm) exceeds 45 per cent. It is expected that by2000 these resources will be the main deposits mined (Zamyatinet aI, 1991).Under real industrial conditions the losses of minus 0.25 mmmetal are 50 per cent and more. The low level of recovery of finegold is observed not only at concentrators equipped with sluices,but also at concentrators equipped with modern diaphragm andpistonless jigs (Table 1).

Jan 1, 1993

By C. Jay Hodgson, Adrienne C. L. Larocque

Abstract -The Mobrun VMS deposit in northwestern Quebec does not fit the classic Noranda­ type model, but exhibits characteristics more consistent with a Mattabi-type deposit. The orebodies are underlain by fragmental volcanic rocks indicative of explosive volcanism in shallow water. Felsic volcanic rocks are more abundant than mafic rocks. Alteration assemblages comprise chlorite, carbonate, sericite, and quartz. Broad semi-conformable alteration occurs high in the footwall to the 1100 lens. Mobrun occurs higher in the stratigraphic sequence than most of the other deposits in the Noranda camp. In this part of the stratigraphy, zones of pervasive carbonatization may be more useful guides for exploration than zones of silicification.

Jan 1, 1993

By Kenyon Burch

ONE of the advantages presented by electric drive in many classes of work is the ease with which the electric motor can be controlled automatically. In a large number of cases certain features of the control are automatic-for example, the rate of acceleration may be limited automatically or the equipment may be stopped automatically at the limit of travel-but the equipment is started and ordinarily is stopped by hand. . In other cases the motion of the machinery is utilized to start, control the: speed, and stop the motor automatically, independently of any operator. A considerable proportion of the large mine hoists now in use have certain automatic features, particularly protective devices against over-winding, and, in some classes of electric hoists, devices for preventing excessive acceleration or retardation. The large automatic hoists discussed in this paper, however, are completely automatic, i.e., capable of snaking their trips without the presence of an operator at the control levers. According to circumstances, various advantages may be obtained by automatic control, chief of which are decreased power consumption', increased precision and safety of operation, and decreased, cost of attendance. The first step in the analysis of a prospective automatic mine hoist is to determine whether automatic operation is feasible at all. If men are to be hoisted, or levels changed, the attention of an operator is required for these purposes; but tinder some conditions it may be entirely practicable and advantageous to build the equipment so that, while provision is made for hoisting mien or changing levels, ore can be hoisted automatically from, any one level. If, however, an operator's attention is required every few minutes for changing levels, handling men or drills, or other work requiring hand control, it is obvious that automatic operation between times will not be of any, practical benefit.

Jan 3, 1916

By G. M. Kintz

It is estimated that 10,000 lives were lost and $285,000,000 worth of property was destroyed by fire in 1937. Of the 103 fatalities in tie petroleum industry in 1938, 36 resulted from fires and explosions.3/ Everyone can help to prevent the tremendous losses, both in life and property, caused annually by fires and explosions, Forest fires occur every year, in which the tremendously intense heat wave ahead of the flame turns beautiful green trees into blazing torches like so much gasoline, vapor, and jumps over the tops of trees to start fires behind the firs fighters; prairie-grass fires occur, and a farmer in the path of the fire must plow a furrow around his home and outbuildings before the flame reaches them; and frequently automobiles are burned up in filling stations. Persons who have witnessed such sights know better than to throw a lighted match, cigarette, cigar, or hot coal from a pipe out of an automobile or to discard a fire or flame of any type in the forest, in the country, or in the city.

Jan 1, 1941

By V. Roze, R. N. Parkinson, R. Shepherd

The alphaDOSIMETER is a complete, integrated system designed to monitor the immediate worksite of underground miners where the disintegration for radon daughters is a risk to the health of mining personnel. The dosimeter weighing little more than one pound is worn by each miner throughout the entire shift and is powered by the miner's cap lamp battery. After this integration period, the unit is connected to a reading network whereupon the day's data is dumped, calculated and stored. Beginning in July 1980, prototype units were subjected to vigorous underground testing in uranium mines in Canada and the United States and in tin mines in Cornwall, U.K. The testing results are summarized and proposals advanced for a typical mine monitoring system utilizing the alphaDOSIMETER.

Jan 1, 1981

By Xiang Lan

A strain of Thiobacillus ferruuxidans No. 8 was isolated from the acidic mine water of an arsenopyrite deposit, South China. It has been found from the experimental results that the growth of bacteria was inhibited by flotation agents. The order of toxic effect of different flotation agents on the growth of Thiobacillus ferrooxidans is ethyl xanthate > butyat ammonium aerofloat > butyl xanthate ? isobutyt xauthate >? flother No. 2 oil. The bioteaching treatment of arsenic and antimony-bearing gold concentrate in Longshan mine, Hunan province, China, was influenced considerably by the presence of flotation agents. The possible causes of the influence of flotation agents were discussed and an improved method was suggested.

Jan 1, 1991

"INTRODUCTION Foam, unless intentionally created, in any industrial process presents operational problems, or at a minimum, is a nuisance. Some foam problems are unique to a given industry and others are common across many industries. A few problems foam presents to any particular industry are: (a) Poor Housekeeping, (b) Environmental impact, (c) Safety Hazards, (d) Slower Production Rates and, (e) Reduced quality of the end product. Defoamers address these issues. Sadly, the assumption in most industries is all defoamers are alike. In reality, a lot of chemistry is involved in the manufacture of even the simplest defoamer sold today and rarely are any two defoamers “just alike”. Today’s defoamers can include polymer chemistry, fatty esters, alkoxylated alcohols, silicone chemistry, silicone surfactants, ethoxylated and propoxylated block polymers, and a tremendous amount of emulsion chemistry just to name a few. This paper will discuss the various types of defoamers, defoaming mechanisms, the advantages and disadvantages of defoamer selections, and how to choose the proper defoamer for your application. Before a discussion of defoamer can be brought about, foam generation and composition must be discussed. WHAT IS FOAM? Foam is a colloidal suspension of a gas dispersed in a liquid. Most often foam consists of air dispersed in water. If a stream of air is introduced into a liquid, the bubbles produced assume a spherical shape. As the density of the bubble is less than the liquid the bubble rises. When the individual bubbles reach and pass through a surfactant free liquid they collapse. Air from the bubble dissipates and the liquid previously surrounding the bubble flows back.It should be noted a pure liquid will not foam. In the case of air dispersed in water a surfactant is necessary to make the water support a stable foam. A surfactant is a term used to describe a surface active agent; a compound with a hydrophilic end and a hydrophobic end on the same molecule."

Jan 1, 2016

By Akira Usui

Iron and manganese are very mobile metallic elements in the surface aqueous environment, particularly in the oceans. The elements are easily precipitated as oxides or dissolved back into water, controlled mainly by redox conditions, and the oxide precipitates often selectively accumulate other metallic elements. We have found clear evidence of fine-scale variations in chemistry, mineralogy, isotope composition and microstructures within various iron-manganese nodules and crusts, such as in the deep-sea basins and seamounts of the Pacific Ocean, and in shallow waters in the Baltic Sea. The patterns of variation with depth (that is time-lapse profiles of the deposits) are often correlated among samples and sometimes between remote localities. These fine-scale variations most probably reflect past depositional conditions and possibly image the environmental change, although they remain to be correlated to any physicochemical, geological, or oceanographic parameters. The hydrogenetic ferromanganese crusts have grown widely in the northwestern Pacific, accelerated by intensive circulation of oxygenated bottom waters during the last several millions of years, or earlier. The fine-scale (in millimeter) in-depth compositional and textural patterns with Be-10 growth-rate curves suggest significant changes in growth rate and also occasionally show a common microstratigraphic pattern among samples. Some of the samples indicate a correlation in growth pattern between remote locations, while others suggest short-range difference of oceanographic conditions with water depths.

Jan 1, 2004

By D McLaughlin

This paper points to the timely importance of commencing a centrally recognised perpetual collection of mineral specimens in the Northern Territory which has as one of its objectives the collection and preservation of Northern Territory minerals of scientific, educational and heritage value. Currently in the Northern Territory there is no government department or institution that has a resourced coordinated state-wide objective to collect and document collectable mineral specimens. Specimens held in storage by the Department of Mines and Energy and the Museum and Art Galleries of the NT are not catalogued and owe their existence to fortuitous circumstances, not as a result of a planned systematic scientific approach to mineralogy. Northern Territory mineral species and unique specimens have and will continue to be driven to extinction while no central and active, recognised repository exists. This situation persists despite the fact mineral production is the Territory's largest income earner. The paper presents the arguments that hopefully will assist decision-makers to commence development of a state mineral collection lodged within an appropriate institution in the Northern Territory.

Jan 1, 1994

By J. G. Wiese

Reagents are added to the flotation process of Merensky Reef ores to achieve specific functions that enable the separation of valuable minerals from gangue minerals on the basis of the difference in their surface properties. However, due to the complexity of the process, the various interactions that occur as well as the incomplete liberation of the ore and range of minerals present, it is difficult to quantify the behaviour of each of the reagents. More specifically, changes made to achieve a particular outcome may have secondary effects that can override the desired effect. If all the effects and interactions can be accounted for, it is possible to manipulate reagent suites and obtain better overall metallurgical performance. This paper discusses the effect of the addition of copper sulphate at different operating points of the recovery of the sulphide minerals. Batch flotation tests indicated that the recovery of chalcopyrite was not affected when operating conditions were varied, whereas pentlandite recovery was strongly affected by the point of reagent addition, and pyrrhotite recovery was enhanced by copper sulphate addition, irrespective of the point of addition, with the extent being dependent on the ore source. Floatable gangue was activated by copper sulphate in the presence of the dithiophosphate collector. Froth stability was also affected by copper sulphate addition.

Jan 1, 2007

By Vladimir Adamek

Due to the variability of subsidence characteristics across the U.S. coalfields, it was concluded that it would be practically impossible to develop a universal predictive model for mining-induced subsidence based on theoretical assumptions. Therefore, an effort was made to find a procedure to develop an empirical subsidence predictive model based on a sufficient Mount of field data from one mining area (in this case the Northern Appalachian Coal Region). It was also thought that this procedure, if successful, could be used as the template for developing predictive capabilities for other coalfields with different subsidence characteristics given a reasonable amount of field data. It has been found, in the Northern Appalachian Coal Region, that the variability of subsidence characteristics can be expressed by a polynomial equation developed through regression analysis of the variable subsidence coefficient and derived directly from the field data. In this study, field data were obtained from 11 Bureau longwall panel studies (16 half profiles) for static subsidence and 14 panels for dynamic subsidence. The effects of lithology, expressed in the form of a variable subsidence coefficient, have been separated for each test site by introducing a correlation between hythetically homogeneous overburden and existing ithological conditions. For each longwall panel, the characteristic of the variable subsidence coefficient was defined along individual static profiles. The definition of mean values with acceptable deviations is the substance of the predictive method. The same procedure was used to develop a predictive model for dynamic subsidence, since it war discovered that the rate of longwall face advance is not a necessary functional parameter. This paper presents the theory, development, and application of the static and dynamic subsidence prediction models.

Jan 1, 1986

By George S. Rice

Foreword Explosion hazards differ widely in the mines of different fields or coal basins. They also differ as between different mines in the same basin or fold, because of variations in gas entering the mines, and because dust conditions and explosion hazards are affected by the mining methods employed and the organization of the work. It is unquestionably true, however, that there are greater differences in explosion hazards in mines of different coal fields or basins than between different mines of the same field or basin. In these respects, the coal fields and individual mines in Alberta are not exceptional. The same conditions obtain in various countries where coal is mined, and are found in single States, as for example in Colorado, where coals are mined ranging in character from sub-bituminous to anthracite, and in attitude from flat horizontal to steeply pitching beds. The U.S. Bureau of Mines, at its experimental mine near Pittsburgh, Pa., has made large-scale tests of the relative explosibility of dusts of coals, ranging in rank from Wyoming sub-bituminous coal containing 19 per cent moisture, to anthracite from Pennsylvania, and including samples from a mine in the Crowsnest Pass district, B.C., and from a Vancouver Island mine. The Bureau has also made similar tests of the dust of coal from a Yorkshire mine which the British Safety-in-Mines Research Board uses as standard.

Jan 1, 1927

By A W. Bewsher, T C. McCu, D B. Mapleson

The Miitel nickel sulfide deposit has been overprinted by a family of late stage structures that have acted as conduits for fluids that have contaminated the orebody with arsenic minerals. This has resulted in highly variable and unpredictable arsenic grades throughout the Miitel orebody. The ore produced from Miitel is processed under a toll-treatment agreement with Western Mining Resources Kambalda Nickel Concentrator. Part of this arrangement includes a financial penalty if monthly average arsenic grades in ore delivered exceed 800 ppm. This constraint has provided an extra challenge to the Miitel mine geologist in addition to daily underground duties. Routine development and stope mapping, close spaced sampling and cross-sectional interpretation were used in building an understanding of the structural controls of arsenic mineralisation and ore repetition at the Miitel nickel mine, and in providing maximum input to mine planning and scheduling. The distribution of structures responsible for arsenic introduction is now well understood from detailed mapping, sampling, and interpretation. By applying these insights to mine scheduling, the operation has successfully managed arsenic levels within the required specifications. Geological mapping has also improved the understanding of the structural complexity of the ore deposit, leading to the addition of ore tonnes and an increased confidence in resource modelling. Regular sampling and tight controls on data quality provided confidence in a strongly skewed arsenic data set. Multiple Indicator Kriging has been used for resource estimation of the arsenic contaminated nickel ore since it allows explicit control of the spatial influence of extreme grades in the positively skewed arsenic sample population. Both the grade control and exploration data sets are used to model the arsenic distribution.

Jan 1, 2003

By R. K. Wharton

A European Directive requires that an explosive which is sold or transported within Europe must meet certain essential safety requirements from 1 January 2003. The assessment and certification of such an explosive is undertaken by an Explosives Notified Body and if the explosive meets the requirements a certificate is issued that allows the affixation of a CE mark. The presence of a CE mark ensures the product free access to European markets. The paper examines the requirements of the Directive, identifies those explosives that come within its scope, considers the role of an Explosives Notified Body, and explains the process of applying for certification.

Jan 1, 2002

By S. Maluadzi, D. Rocchi, S. Luyckx, S. S. Potgieter-Vermaak, C. Machio, J. H. Potgieter

The aim of this work was to compare the corrosion behaviour of thermal spray WC ? based coatings before and after annealing. X-ray diffraction (XRD) was used to determine the phases present in the coatings at various stages. The corrosion resistance of the coatings was measured using electrochemical and immersion corrosion tests. The results obtained from electrochemical corrosion (quantified by corrosion current density) and immersion corrosion tests showed that annealing appears to decrease the corrosion resistance of the coatings. From the XRD results it was determined that the phases that corroded preferentially were cobalt (Co), eta (Co6W6C) and W2C. Keywords: Corrosion, thermal spray, coatings, hardmetals.

Jan 1, 2006

By J O. Okonkwo

AngloGold operates various gold mines in South Africa, the largest of which are situated in the North West province. The impact of AngloGold Vaal River mining operations on the environment and, specifically, on aquifers and groundwater is assessed. The location of such aquifers and plumes is determined by remote-sensing and ground-sensing operations, followed up with the correct placement of monitoring boreholes from which information such as water rest levels, chemistry and geological data is gathered. This study utilises an integrated approach consisting of the following mutually reinforcing phases: Phase 1: Airborne multi spectral scanning; Phase 2: Airborne thermal remote sensing; Phase 3: Ground resistivity survey; Phase 4: Borehole placement; and Phase 5: Sampling and monitoring. The integration of the investigation tools and phases in use at AngloGold Vaal River has been found to be very useful in determining the exact sources of contamination, the direction of flow of such contamination, the positioning of interceptive measures and the analysis of such contamination. This adopted approach will enable the development of flow transport models that will further enhance our knowledge of contaminants in aquifers at the mine and enable management to conduct educated interventions.

Jan 1, 2003

The introduction of gravimetric sampling of respirable dust in the mining industry ne- cessitated the standardisation of techniques. The paper reviews the legislation con- trolling respirable dust monitoring for risk assessment purposes, it discusses the actions taken to introduce gravimetric sampling in collieries and it summarises the proposed guidelines. In conclusion, some of the results of dust surveys conducted in accordance with the proposed strategy are discussed.

Jan 1, 1988

By S. Banisi, M. Poorkani, M. Farzaneh, M. Askari

"At the Sarcheshmeh copper mine 40,000 t of ore per day with an average grade of 0.9 % Cu is ground to 70% passing 75 microns. Grinding is effected in 8 parallel lines of 8 x 5 m ball mills in a closed circuit with cyclones. The make-up balls are 80-mm forged alloy steel balls and the average ball consumption is 750 gh of ore ground. In order to optimize ball size distribution inside the mill, based on the previous investigation instead of using only 80 mm make-up balls a combination of 80 and 60 mm (75% to 25% by weight) ball charge was used in one of the mills. To evaluate the performance of three ball types namely forged alloy steel balls (A), ductile cast iron (C), high chromium cast iron (D) and also a combined (80 and 60 mm) charge of forged alloy steel balls (B), four identical parallel mills were charged accordingly. These four mills were sampled during a period of six months. The amount of material finer than 75 microns of cyclone overflows was selected as a criterion for the performance evaluation. It was observed that in a mill with the combined make-up balls the amount of fine produced was 4% higher than the other mills. The consumption of ball types A, C and D were 730, 710 and 534 g/t, respectively. The results of laboratory flotation tests showed that due to an improvement in the production of fines an increase of 1.4% in the overall copper recovery is obtainable. Due to the promising results, the new make-up ball regime was implemented in all mills in the plant.INTRODUCTIONThe Sarcheshmeh copper ore body which may rank as third or fourth largest in the world contains 1 billion tonnes averaging 0.90 % copper and 0.03 % molybdenum. It is located southeast of Iran and has been processing 40,000 t/d of ore since 1982. The mine produces 100,000 tonnes of copper and 2,200 tonnes of molybednite concentrate per year. After three stages of crushing, the ore with a F80 of 12.7 mm is fed to 8 parallel ball mills in closed circuit with cyclones to produce a product 70% finer than 75 microns. The concentrate of the first stage of flotation is reground and the tailing constitutes the main component of the plant final tailings. A concentrate with an average grade of 31% Cu is obtained after cleaning and re-cleaning stages. Total recovery of the plant varies between 83 and 87 % depending on the operating conditions and ore type."

Jan 1, 2002

By J. H. Nead

The experiments herein described were undertaken with a view to investigating thoroughly the influence of carbon on the tensile and impact physical properties of carbon steel. The original comprehensive plan included investigation of a series of steels with varying carbon contents over a wide range of heat treatments. These were to be studied as to their static tensile qualities, and also their resistance to shock as measured by the Charpy impact bending test. A thorough metallographic examination was likewise included in the schedule. The Charpy tests and the metallographic examination have not been completed to date, and are accordingly withheld for another report. All heat treatments, however, have been made, and the static tensile tests have been completed. A description of the procedure of the experiment and the results thus far obtained are therefore reported herein. Conclusions No attempt is made to draw general conclusions from these experiments, but the curves and the data are submitted as being of general importance and wide applicability. Composition of Materials An attempt was made to secure steels increasing in carbon by increments of 0.1 per cent. from 0.1 per cent. up to 0.8 per cent., and from that composition to 1.6 per cent. by increments of 0.2 per cent. Actually, however, steels of the composition given in Table I were procured, and as the carbon contents were arranged sufficiently well so that satisfactory curves could be drawn showing the relation between carbon content and other properties, these steels were used in the experiments.

Jan 1, 1916

By E. A. Lauha

The Goldstrike Mine is in Eureka County, Nevada, U.S.A., approximately 23 miles northwest of the town of Carlin. The mine is at the north end of the Tuscarora Spur of the Tuscarora Mountains at elevations of 5,300 feet to 5,950 feet. It is part of the Bluestar/Goldstrike sub-district of the Carlin Trend, a northwest alignment of sediment hosted, disseminated gold deposits. The Carlin Trend includes over 15 major gold deposits with production, reserves and geological resources of approximately 65 million ounces of gold (Figure 1). In the Bluestar/Goldstrike sub-district, there are seven major deposits: Betze, Lower Post, Post, Genesis, Bluestar, Purple Vein and Deep Star, plus numerous smaller deposits (Figure 2). Production, reserves and resources for the sub-district are approximately 40 million ounces. Betze and Purple Vein are located on property controlled by Barrick Goldstrike Mines and Bluestar and Genesis on Newmont Gold property. Post, Lower Post and Deep Star occur both on Barrick and Newmont property.

Jan 1, 1993